The present invention relates to a clamping arrangement for seat carriers of chairs, in particular office swivel chairs, with the characteristics of the generic part of Claim 1.
A clamping arrangement for seat carriers of chairs, in particular office swivel chairs, whereby the seat carrier is provided with at least two parts which can be pivoted in relation to each other about a common axis and to each of which a lamellar stack is hinged, whereby the lamellar stacks intermesh with each other, whereby both lamellar stacks are provided with recesses through which they are hinged to a common transverse pin, and the recesses of at least one of the lamellar stacks allow the lamellar stack to move across the axis of the common pin, and whereby means are provided which can be moved into and out of a clamped position with the lamellar blades of both stacks, whereby the clamping means are supported on one of the two parts or another additional part of the seat carrier, is known, for example, from DE-U-295 02 040. The two parts which can be pivoted in relation to each other are the base structure which rests on the support column with the pedestal and the back rest carrier, whereby the clamping mechanism is supported in the base part. The clamping means are designed as a cylindrical plastic roller with flattened zones. When the full diameter of the roller engages between an exterior wall of the base part and a stop for the lamellar blades, the latter are clamped. It was found that clamping, which takes place substantially along two lines, is not satisfactory in every case.
The objective of the present invention is to develop a clamping arrangement of the type mentioned earlier to the effect that the a clamping state can be achieved which is secure and permanent, and that users physically perceive the adjustment from clamping to unclamping as they operate the arrangement.
According to the invention, a clamping arrangement of the type mentioned earlier is characterized in that the clamping means are pivotably arranged in the part, whereby their swivel axis extends across the axis of the common pin, so that means for the pivoting of the clamping means are available which extend outside the seat carrier and can be activated from the outside, and that the clamping means are provided with at least two surfaces arranged at an angle to each other, one of which, when in clamped position, abuts to and clamps the lamellar blades or a flange or collar acting upon said blades.
According to an advantageous embodiment of the invention, the clamping means are an elongated clamping body whose longitudinal axis is parallel to the lamellar blades, whereby the clamping body is provided with a drilled hole, which becomes conically wider on both sides, for the common pin or a sleeve surrounding same, whereby the surfaces arranged at an angle to each other are parallel to the longitudinal axis of the lamellar blades and whereby the clamping body is provided with a drilled hole for a pivot arm rigidly connected with same which extends outside the seat carrier on that side of the clamping body which faces away from the lamellar blades. At a distance from the lamellar stacks, the clamping body is provided with a second drilled hole, which becomes conically wider on both sides, and is mounted with this second drilled hole on a retaining pin arranged parallel to the common pin in the seat carrier. On the retaining pin, a compression spring is arranged which applies a force to the clamping body opposite to the clamping direction.
For example, the clamping body can be supported in the seat carrier against the force of a spring; preferably, however, it consists of a molded plastic part, whose side opposite the lamellar blades is supported by support surfaces on a side wall of a part of the seat carrier, whereby each support surface is parallel to one of the surfaces arranged at an angle to each other.
According to a preferred embodiment of the invention, the common pin and the retaining pin are arranged in the side walls of a part of the seat carrier with a U-shaped cross section, and the clamping body is supported on one side of the interior wall of the part, whereby the lamellar blades, when in clamped position, are pressed against the other interior wall or against a stop rigidly connected to it or to the common bolt.
Preferably, there are two surfaces arranged at an angle to each other and two support surfaces, whereby the surfaces arranged at an angle to each other and the support surfaces enclose obtuse angles of equal size, so that when the clamping body is pivoted about its longitudinal axis from one pair of surfaces to the other, the apical lines press simultaneously against the interior wall and the lamellar blades or against a flange acting upon the blades, thus making the adjustment physically perceivable.
According to a special embodiment of the invention, the common bolt is surrounded by a slidingly mounted sleeve which is provided with a flange, whereby in clamped position the clamping body presses upon the flange, and the flange abuts to the lamellar stacks, whereby the lamellar stacks on the other side abut to a stop which is rigidly connected to the common pin, and whereby a spring is provided which is supported on the stop and which has a tendency of pressing the sleeve against the clamping direction.